Baseflow and Runoff Event Metal Concentrations,Partition and Its Relation with Physicochemical Variables in an Agroforestry Catchment          下载免费PDF全文

Laura Palleiro  María Luz Rodríguez‐Blanco  María Mercedes Taboada‐Castro  María Teresa Taboada‐Castro 《洁净——土壤、空气、水》2014,42(4):462-471

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磁倾子矢量的图示分析及其应用研究   总被引：16，自引：0，他引：16  

陈小斌  赵国泽  詹艳  汤吉  邓前辉  王继军  陈树岩  汪卫毛  王友胜 《地学前缘》2004,11(4):626-636

对磁倾子矢量的图示方式进行了研究。根据平面上矢量与复数之间的关系 ,在原有Schmuck er感应矢量定义的基础上 ,提出了虚感应矢量及其他图示矢量的新定义 ,并对其旋转特性进行了分析 ;根据感应矢量的旋转不变特性以及其在二维情况下的特点定义了倾子二维近似度 ,该参数可作为定性判别某点电性结构二维性的一种衡量标准。利用二维和三维模型对新提出的倾子图示方式进行了计算 ,并将其应用于海原大震区的实际资料的处理和解释当中 ,主要讨论了感应矢量尤其是虚感应矢量的响应特征。理论计算和实际应用结果表明本文所定义的感应矢量和倾子二维偏离度有着较为明确的物理意义 ,对于MT资料处理和解释有一定的指导作用  相似文献   

Wind direction and complex sediment transport response across a beach–dune system     

Bernard O. Bauer  Robin G. D. Davidson‐Arnott  Ian J. Walker  Patrick A. Hesp  Jeff Ollerhead 《地球表面变化过程与地形》2012,37(15):1661-1677

Evidence from a field study on wind flow and sediment transport across a beach–dune system under onshore and offshore conditions (including oblique approach angles) indicates that sediment transport response on the back‐beach and stoss slope of the foredune can be exceedingly complex. The upper‐air flow – measured by a sonic anemometer at the top of a 3·5 m tower located on the dune crest – is similar to regional wind records obtained from a nearby meteorological station, but quite different from the near‐surface flow field measured locally across the beach–dune profile by sonic anemometers positioned 20 cm above the sand surface. Flow–form interaction at macro and micro scales leads to strong modulation of the near‐surface wind vectors, including wind speed reductions (due to surface roughness drag and adverse pressure effects induced by the dune) and wind speed increases (due to flow compression toward the top of the dune) as well as pronounced topographic steering during oblique wind approach angles. A conceptual model is proposed, building on the ideas of Sweet and Kocurek (Sedimentology 37 : 1023–1038, 1990), Walker and Nickling (Earth Surface Processes and Landforms 28 : 111–1124, 2002), and Lynch et al. (Earth Surface Processes and Landforms 33 : 991–1005, 2008, Geomorphology 105 : 139–146, 2010), which shows how near‐surface wind vectors are altered for four regional wind conditions: (a) onshore, detached; (b) onshore‐oblique, attached and deflected; (c) offshore, detached; and (d) offshore‐oblique, attached and deflected. High‐frequency measurements of sediment transport intensity during these different events demonstrate that predictions of sediment flux using standard equations driven by regional wind statistics would by unreliable and misleading. It is recommended that field studies routinely implement experimental designs that treat the near‐surface wind field as comprising true vector quantities (with speed and direction) in order that a more robust linkage between the regional (upper air) wind field and the sediment transport response across the beach–dune profile be established. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

THE USE OF GRAIN SIZE TRENDS IN MARINE SEDIMENT DYNAMICS： A REVIEW   总被引：10，自引：0，他引：10  

MichaelCollins  高抒 《中国海洋湖沼学报》2001,19(3):265-271

Spatial changes in grain size parameters (i. e. grain size trends) contain information on sediment transport patterns. An analytical procedure has been proposed to transform the grain size trends into an image of trend vectors, which may represent net sediment lransport pathways. A fundamental assumption for such an approach is that the frequency of occurrence of the trend adopted is much higher in the transport direction, than in any of other directions. Preliminary studies show agreement between this assumption and observations. However, further investigations into the physical processes and mechanisms for the formation of grain size trends are required to improve the technique, including flume experiments and numerical modeling. Moreover, attention should be paid to the trends associated with finegrained sediment, for the method of grain size trend analysis is so far designed for coarse-grained material only. The processes of flocculation during settling and the wash-load property must be considered. Appropriate interpretation of grain size data will improve our understanding of the physics of granular materials.  相似文献   

重庆市气温及降水变化的奇异谱分析   总被引：5，自引：4，他引：5  

李永华  刘德  朱业玉  高阳华  毛文书 《高原气象》2005,24(5):798-804

采用奇异谱分析（SSA）方法对重庆市长年代逐月地面气温及降水资料进行了分析，结果表明，重庆市气温序列存在准2年、准4年周期及16个月的年际振荡特征；而降水序列有准4年、准2年周期及8～16个月的年、季振荡特征。  相似文献   

多维分形奇异功率谱分析与应用          下载免费PDF全文

李庆谋;  ;  刘少华; 《地球物理学进展》2005,20(4)

地球物理信号中普遍含有噪声，消除噪声是地球物理信号处理中的关键技术之一.奇异功率谱分析（SSA）是在状态空间（又称相空间）中研究（系统）动力学、非线性科学与混沌现象的方法.本文在状态空间中通过SSA分解，研究、应用地球物理序列的尺度不变性进行多维分形滤波：通过在状态空间的SSA分解，构造了经验正交函数系（EOF）；在EOF子空间中定义了两种尺度与测度后，发现了两种测度与尺度皆在多个尺度范围内存在尺度不变性；利用这种尺度~测度的尺度不变性，设计、实现了多维分形奇异功率谱(MSSA)滤波模型；处理解释了大洋钻探（ODP）1143A孔岩芯自然反射性（NGR）资料；Fourier功率谱分析结果证明，MSSA能有效地压制噪声，提取有用信号.研究得出，嵌入维数对MSSA基本无影响（小于1/1000），多维分形滤波器（MSSA）能有效压制噪声或提取有用信号.  相似文献   

Local and global shape functions in a boundary element formulation for the calculation of traffic induced vibrations   总被引：1，自引：1，他引：1  

S. Franois  G. Lombaert  G. Degrande 《Soil Dynamics and Earthquake Engineering》2005,25(11):839-856

This paper compares the use of local and global shape functions in a boundary element method that is used in a prediction model for traffic induced vibrations. The boundary element formulation describes the interaction problem between a linear elastic layered half-space and a longitudinally invariant structure representing a road or a railway track. The boundary element formulation in the frequency–wavenumber domain is obtained by means of a weighted residual method. Constant element shape functions, as well as Legendre and Chebyshev shape functions are considered. Their effect on both accuracy and computational effort is investigated. The presence of a singularity in the Chebyshev based shape functions allows to obtain a better approximation for the soil tractions. The theory is applied to road traffic induced vibrations where the response is calculated in a large number of output points.  相似文献   

总体最小二乘拟合问题求解方法的比较研究     

龚循强  刘国祥  李志林  周秀芳 《测绘科学》2014,39(9)

目前对总体最小二乘求解方法的研究,出现了奇异值分解的总体最小二乘法、顾及自变量和因变量误差的总体最小二乘法及正交总体最小二乘法.在模型推导的基础上,本文对3种总体最小二乘法在直线和平面拟合中求解的参数及其精度进行了分析,通过与最小二乘法的比较表明,总体最小二乘法得到的拟合结果更加稳健,且以正交总体最小二乘法的拟合结果为最优.  相似文献   

东亚北部地区现代板块构造的运动学分析   总被引：4，自引：1，他引：3       下载免费PDF全文

魏东平  濑野徹三 《地球物理学报》2000,43(1):54-63

从原欧亚板块划出阿穆利亚微板块,并建立一个包括太平洋、北美、欧亚、鄂霍次克及菲律宾海等板块在内的６板块系统,利用地震滑移矢量,转换断层走向,洋中脊扩展速率,以及最新的ＧＰＳ观测资料,采用Ｍｏｎｔｅ－Ｃａｒｌｏ盒子法,反演得到该６板块系统的欧拉运动矢量．本文得到的有关欧拉矢量为：ＡＭ-ＥＵ（６０．４２°Ｎ,１２３．２５°Ｅ,０．０２５°／Ｍａ）,ＡＭ-ＯＫ（５３．２０°Ｎ,１４１．９５°Ｅ,０．４７６°／Ｍａ）以及ＡＭ-ＰＨ（５０．８４°Ｎ,１５８.１３°Ｅ,１.２０４°／Ｍａ）,ＡＭ－ＥＵ的欧拉运动极点位于贝加尔隆起的东北及斯塔诺夫山脉的西北,并给出在贝加尔隆起有０．４－０．７ｍｍ／ａ的扩张,与从地质学证据得到的估计结果一致;由ＡＭ－ＯＫ及ＡＭ－ＰＨ欧拉运动矢量可以分别得到日本海东缘的６-１５ｍｍ／ａ及日本南海地槽带的５１－６６ｍｍ／ａ收敛速率,与最新的ＧＰＳ观测结果并不一致．因此,东亚北部地区存在独立的南中国微板块及其它亚尺度的微板块,可以更好地描述该地区现今板块构造的运动规律．  相似文献   

Evaluation of Vector Winds Observed by NSCAT in the Seas around Japan     

Harunobu Masuko  Kohei Arai  Naoto Ebuchi  Masanori Konda  Masahisa Kubota  Kunio Kutsuwada  Teruko Manabe  Akira Mukaida  Tetsuo Nakazawa  Atsushi Nomura  Akira Shibata  Yoshihiko Tahara 《Journal of Oceanography》2000,56(5):495-505

In order to validate wind vectors derived from the NASA Scatterometer (NSCAT), two NSCAT wind products of different spatial resolutions are compared with observations by buoys and research vessels in the seas around Japan. In general, the NSCAT winds agree well with the wind data from the buoys and vessels. It is shown that the root-mean-square (rms) difference between NSCAT-derived wind speeds and the buoy observations is 1.7 ms^–1, which satisfies the mission requirement of accuracy, 2 ms^–1. However, the rms difference of wind directions is slightly larger than the mission requirement, 20°. This result does not agree with those of previous studies on validation of the NSCAT-derived wind vectors using buoy observations, and is considered to be due to differences in the buoy observation systems. It is also shown that there are no significant systematic trends of the NSCAT wind speed and direction depending on the wind speed and incidence angle. Comparison with ship winds shows that the NSCAT wind speeds are lower than those observed by the research vessels by about 0.7 ms^–1 and this bias is twice as large for data observed by moving ships than by stationary ships. This result suggests that the ship winds may be influenced by errors caused by ship's motion, such as pitching and rolling.  相似文献